The present invention relates to a device for the automatic regulation of the quantity of adhesive deposited in flexible film rolling machines.
It is known that the rolling machines used for the production of flexible film composites are composed of a coating and a bonding column, joined to each other by an upper frame.
The coating column consists of a metal structure bearing: a coating group for adhesives without solvents, a heating station, a first film unwinding unit to be subjected to the coating operation, and a control unit.
The bonding column consists in a metallic structure holding the following: a bonding unit and the heating unit, a second unwinding unit that participates in the bonding process, the winding unit and the second control unit.
In the coating units the solvent-free adhesive is fed discontinuously from a (prevalently piston-type) mixer, capable of volumetrically regulating the ratio between the two components of the adhesive system.
The pre-mixed adhesive is loaded in a space formed between two cylinders of the coating goup. Said cylinders form a container for the adhesive.
One of these cylinders is prevalently still, while the other rotates at a certain speed and is in contact with a connecting cylinder rotating at a higher speed.
The connecting cylinder is also in contact with the film dragging cylinder an its pressing cylinder. The latter rotate at the speed of the film, which is greater than that of the connecting film.
The adhesive is therefore drawn from its holding tray, meaning the first two cylinders, while using speeds ever greater than those of the cylinders following them.
By regulating the relative speed of the connecting cylinder by means of a potentiometer, the operator can increase or decrease the basic weight of the adhesive deposited on the rolling film.
The control of the basic weights deposited is done by weighing the rolled film and calculating the difference with the same film after the adhesive has been removed. However, this method is rather approximate, especially when also considering the tiny quantities of adhesive deposited.
While operating the pre-determination of the quantities deposited is left up to the experience and sensitivity of the operator and controlled by the mentioned system. The purpose of this invention is therefore to produce a device for the automatic regulation of the quantity of adhesive in flexible film rolling machines capable of resolving the mentioned problems, while achieving better operating characteristics and a better control of finished product quality.
These and other purposes are achieved by a device or the automatic regulation of the quantity of adhesive in flexible film rolling machines wherein said rolling machine (20) includes a coating column (21) and a bonding claim (22), joined to each other by an upper frame (23), and wherein a quantity of premixed adhesive is charged to a container (32) generally formed by a space formed between two cylinders set side by side (13, 14) and transported by the motion of one of said adjacent cylinders (13) to a film (31) dragging cylinder (15), wherein said adhesive is fed continuously from an automatic mixer (40), capable of varying the quantities fed per unit time depending on pre-established basic weights, and on said rolling machine""s (20) instantaneous speed, said adjacent cylinders (12, 13) having a speed which is automatically varied so as to increase or decrease the quantity of adhesive deposited on said film (31).